- A boat takes half time in moving a certain distance downstream than upstream. What is the ratio between rate of boat in still water and rate of current?
Let the distance be xkm.
2x/(u+v) = x/ (u-v)
2u – 2v = u+v
- A boat covers a certain distance downstream in 2 hour, while it comes back in 2 1/2 hours. If the speed of the stream be 3 km/hr, what is the speed of the boat in still water?
Speed downstream = (u + 3) km/hr
Speed upstream = (u- 3) km/hr
(u+ 3) *2 = (u- 3) *5/2
- If sum of upstream and downstream speed of a boat is 82 kmph, and the boat travels 105 km. upstream in 3 hr, Find the time taken by boat to cover 141 km downstream.
Speed of Upstream =u-v
Speed of Downstream = u+v
41 – v = 105/3 = 35
v = 6 km/hr
u + v= 141/t
41 + 6 = 141/t
t = 141/47 = 3 hrs.
- A boatman goes 4 km against the current of the stream in 1 hour and goes 2 km along the current in 10 minutes. How long will it take to go 24 km in stationary water?
Speed in still water=(12+4)/2
For 24 km time=24/8
- The speed of a boat in still water is 15 km/hr. It can go 30 km upstream and return downstream to the original point in 4 hrs 30 min. The speed of the stream is:
D=t [(u2 – v2) /2u] 30 = 4 ½ *[(152 – v2) /2*15] 30=9/2 (225- v2)/30
- A boat takes 12 hr to travel a distance upstream and takes 6 hr to travel the same distance downstream. If the speed of the boat in still water is 4 kmph, then what is the speed of the stream?
6(3+v) = 12(3-v)
- A man can row 8 km/hr in still water. If it takes him thrice as long to row up, as to row down the river, then the rate of current in the stream would be
(8-v)*3t = (8+v)*t
- A man can row three-quarters of a kilometer against the stream in 45/4 minutes and return in 15/2 minutes. The speed of the stream
Upstream in 45/4min=3/4km
In 1 hr =3/4*4/45*60
Downstream in 15/2min=3/4km
In 1 hr=3/4*2/15*60
- A boat running downstream covers 28 kms in 7 hours, while for covering the same distance upstream it takes 4 hours. What is the speed of the boat in still water and ?
Speed of the boat u=(4+7) /2
- A man can row 8 km/hr in still water. If the river is running at 3 km/hr, it takes 3 hours more in upstream than to go downstream for the same distance. How far is the place?
D=3 (82 -32)/(2*3)